The language gaijins often use in Japan. "Gaijin" is a Japanese word referring to "foreigners".

Gaijinese can be Japanese spoken with a strange anglicized accent or Japanese that's slightly off due to mistakes in grammar (Japanese spoken with English or another language's grammatical structures), otherwise known as "hen na nihongo" (strange Japanese).

Gaijinese could also be English spoken with inclusion of many Japanese words; for example, "Oh, that looks so abunai dangerous", "hahah! he is so omoshiroi interesting/funny", etc.

I speak Gaijinese so only other foreigners in Japan can understand me.

Huh? What are you saying? That's not really Japanese, man! It's Gaijinese!